The explosions of Internet of Things industry have been bringing more and more smart devices (SDs) into business and people's daily life. This creates new opportunities to build applications that better integrate real-time state of the physical world and requires agility for the software to accommodate customers' requirements. Nevertheless, devices are usually provided by different manufacturers, and applications are independently constructed based on their own infrastructures with little interoperability. Web of Things concept has enabled the interoperability between devices by RESTful web service in a light-weight way; however, it make less efforts to discuss how to integrate devices into complex business environment. Service-Oriented Architecture and Business Process Management approach are becoming applicable to embedded real-world devices and provide flexible service composition. However, it is based on WS-* web service specification which is too heavy and complex for devices and not compatible to RESTful style. In such situation, integrating device into business application with simplicity and providing agility composition of service based on device are significant challenges. We propose a web-based two-layered integration framework that enables SD to integrate with each other via light-weight interface and other back-end applications into agile business process. A real-life use case on elderly care is studied in detail based on the framework.